Drill Down behaviour problem

[Revelator80]

Hi,
I have a list report based on DMR which has two columns for Category and Customer Sector with spend and target information data shown. The category and customer information is hierarchical and I have enabled drill up/down on the report. What I need is the ability to specify that when a sector is selected, only the category that you have clicked from is brought back on the drill (e.g. Health exists in both IT and Finance categories, if I click the Health sector in Finance I only want to see the next level down for Finance).
Any suggestions?